Malignant tumors are often treated by surgical resection of the tumor to remove as much of the tumor as possible. Infiltration of the tumor cells into normal tissue surrounding the tumor, however, can limit the therapeutic value of surgical resection because the infiltration can be difficult or impossible to treat surgically. Radiation therapy can be used to supplement surgical resection by targeting the residual malignant cells after resection, with the goal of sterilizing them, reducing the rate of recurrence or delaying the time to recurrence. Radiation therapy can be administered through one of several methods, or a combination of methods, including permanent or temporary interstitial brachytherapy, and external-beam radiation.
Brachytherapy refers to radiation therapy delivered by a spatially confined source of therapeutic rays inserted into the body at or near a tumor or other proliferative tissue disease site. For example, brachytherapy can be performed by implanting radiation sources directly into the tissue to be treated. Brachytherapy is most appropriate where 1) malignant tumor regrowth occurs locally, within 2 or 3 cm of the original boundary of the primary tumor site; 2) radiation therapy is a proven treatment for controlling the growth of the malignant tumor; and 3) there is a radiation dose-response relationship for the malignant tumor, but the dose that can be given safely with conventional external beam radiotherapy is limited by the tolerance or normal tissue. In brachytherapy, radiation doses are highest in close proximity to the radiotherapeutic source, providing a high tumor dose while sparing surrounding normal tissue.
Prior art brachytherapy devices have provided a number of advancements in the delivery of radiation to target tissue. For example, Winkler U.S. Pat. No. 6,413,204 describes a brachytherapy method and apparatus for treating tissue surrounding a surgically excised tumor with radioactive emissions to kill cancer cells that may be present in the tissue surrounding the excised tumor. The radiation is delivered in a predetermined dose range defined as being between a minimum prescribed absorbed dose for delivering therapeutic effects to tissue that may include cancer cells, and a maximum prescribed absorbed dose above which healthy tissue necrosis may result. The resulting treatment helps to prevent over-exposure to tissue at or near the brachytherapy device, while still delivering the minimum prescribed dose at the maximum prescribed distance from the device.
Brachytherapy is useful for treating malignant brain and breast tumors, among others. However, malignant tumors in other regions of the body, such as load bearing regions, can provide particular challenges. For example, malignant tumors related to the spinal column often require surgical resection followed by stabilization to promote proper healing. Surgical stabilization can be performed in an open procedure where a surgeon places the patient's bone, bones, or other load bearing structure in a desired position that remains stable while the patient is located in the operating room. Additionally, stabilization devices such as cages used in spinal fusion procedures can be implanted to stabilize the load-bearing region. Still further, the stabilization could be achieved using expandable bodies such as those described in U.S. Pat. No. 6,248,110 entitled “Systems and Methods for Treating Fractured or Diseased Bone Using Expandable Bodies,” issued on Jun. 19, 2001 to Reiley et al., which patent is hereby incorporated by reference.
Treatments utilizing such expandable bodies for stabilization include insertion of the expandable body (e.g., a balloon) to compress cancellous bone and provide an interior cavity. For example, the expandable body can be inflated inside a damaged or weakened vertebral body. The interior cavity then receives a filling material, such as a cement-like material, which hardens and provides renewed structural support. Unfortunately, such procedures limit the access of traditional balloon catheter devices used to deliver brachytherapy radiation to soft tissue.
As such, while advancements have improved the treatment of proliferative tissue diseases, some challenges remain. In particular, delivering brachytherapy radiation to the load bearing aspects of a patient's body (e.g., tissue of or adjacent to vertebral bodies) in combination with a stabilization procedure has proven difficult.